Producing wrought shapes of manganese steel.



UNITED STATES PATENT OFFICE.

WINF IELD S. POTTER, 0 F PITTSBURGH, PENNSYLVANIA.

PRODUCING WROUG-HT SHAPES OF MANGANESE STEEL.

Patented Sept. 10, 1918.

No Drawing. Application filed May 11, 1914, Serial No. 837,662. RenewedJune .1, 1918. Serial No. 237,821.

To all whom it may concern: Be it known that I, WINFIELD S. POTTER, acitizen of the UnitedStates, residing at Pittsburgh, Allegheny county,State of Pennsylvania, have invented certain new and useful Improvementsin Producing duction of wrought shapes of manganese steel; that is tosay, steel containing over 52% manganese, with or without silicon oralloying metals such as chromium or nickel, and containing any suitableproportion of carbon, (for instance, from 25% to 2.25% of carbon).

I have found that a critical point exists in manganese steel, (usuallyat above 825 0., or above, according to analysis) above which carbidswhich have previously separated out, both within and between the grainsof the steel, and also the excess carbids of the separated eutectic, arere-absorbed to a greater or less extent by the mixed crystals of themetal, the completeness of the reabsorption-depending, upon the analysisof the steel, the extent of the separation of carbids and eutectic asdetermined by the conditions of the cooling of the ingot from the heatof casting, and depending upon the time employed in heating the steel upthrough a critical range having its upper limit at about 825 0., anddepending furtherupon the time during which the steel is maintained atthe selected temperature above said critical point'.

I have also found thatwhen a manganese steel ingot has been first cooleddown in part from the heat of casting, (for example, when it has beencooled down to a temperature of say 700 0.), it may be brought into acondition suitable for forging or reduction to bloom, billet, or slabform by moderate or progressive rolling, by heating the ingot to atemperature above the said critical point lying atabout 825 0., andholding it at the temperature to which it has thus been heated for asuitable number of hours, depending upon the roportion of separatedcarbids and eutectic present as determined by the conditions of thecooling of the ingot fromthe heat of casting, and also depending uponthe analysis of the steel.

Where the ingot, in cooling from the heat of casting has dropped belowthe critical temperature lying at about 825 0., or

thereabout, and enters the critical range extending downward therefromto about 7 50 0., martensitic structures are developed, due to theseparation of carbids within the grains of the steel. These structuresare removed as the steel is heated up through and above the saidcritical range of temperature.

The absorption of the separated carbids and the excess carbids of theeutectic may, in accordance with the present invention, beeffected, bysutliciently prolonged heating, at a temperature above the criticaltemperature lying at 825 0., or thereabout, and may be almost completeat temperatures within 200 0., above the said critical temperature, thetime required for heating, generally speaking, being inverselyproportional, to the temperature. At temperatures exceeding 1025 grainsmore rapidly and freely and becomes weaker and more ductile. It ischaracteristic of my present invention, therefore, that the reabsorbtionof the separated carbids and of the excess carbids of the eutectic takesplace at a relatively low temperature, and that the subse uent heatingto higher temperatures, after t e desired re-' absorption has beensubstantially accomplished, is for the purpose of imparting to the metala ductility reater or less in amount according to the higher temperatureselected, appropriate to the final reduction intended.

In practice, the manganese steel ingot will either be permitted to coolfrom the heat of casting to say 700 0., and then reheated through thecritical range beginning at say 750 0., to and above theaforesaid'critical temperature lying at about 825 0., or thereabout; or,the cooling of the ingot will be interrupted at an appropriatetemperature within the range of 200" 0., or thereabout, above the saidcritical temperature of 825 0. An appropriate temperature at which tobegin the prolonged heating within the range above 825 0., orthereabout, will usually lie between 900 0., and 1000 0.,

0., the metal rebut will be eater or less according to the analysis of te steel.

When the piece to be heated is at the appropriate temperature within therange of 200 (3., above the critical temperature, lying at about 825?(1., or thereabout, it is held at, the temperature selected, for aconsiderable time. For instance, with a manganese steel ingot ofordinary analysis, 20 inches square, the time of heatmg, atsay 900 0.,to 950 C., in a soaking pit, would be from 10 to 15 hours, or evenlonger. The prolonged heating, in any case, will be continued for agreater or lesser time, accordm to the size and analysis of the ingot,until the greater ortion of the carbids and the excess carbic s of theeutectic, separated out during the time when the ingot wascooling fromthe heat of casting, will be re-absorbed and taken into solution by themix crystals of the metal.

The ingot .may thereupon be Withdrawn from the soakin pit andimmediately subjected to a moderate reducing operation, which mayconsist of hammer or ressforging, or rollinghwith a light or mo cratereduction with eac pass of the rolls; whereupon it may be cut intolengths, as blooms, billets, or s abs, as may be required.

The bloom, billet or slab, resulting from this first forgin or rollingoperation, may then be reheate to such temperature as is required forthe succeeding forming operation; If the further forming required is butslight, the bloom, billet or slab, may be reheated,t0 an equalizedtemperature as low as 900 C. Ordinarily, however, it will be found moreexpedient to heat the bloom, billet or slab, to an equalized temperaturewithin the range of 1025 C. to 1200 C. (or even higher), and for suchtime as may be necessary to freely regrain the steel and to bring it toa ductility aplproprlate for the forming of the bar or o er final shaperequired.

In some instances, the ductility of the ingot, at the termination of theprolonged heating at a temperature Within the range of 200 0., above thecritical temperature lying at 825 (1, or thereabout, will sulfice forthe particular" final forming intended,

without reheating; and, in such cases, after the initial reduction, theingot will be immediately rolled or otherwise brought to final fo When,in the secondar .formin o eration hereinbefore indicate the stee iseated to temperatures above 1025 C., or thereabout, such of the excesscarbids of the eutectic as ma not have been reabsorbed during theheating for the preliminary forgin or rolling operation will be broughtinto so ution and absorbed, and the product will be correspondingly moreuniform than if the heating for the secondary rolling or forging locatedat about. 825 (3., for a su operation had been restricted to a lowertemperature than 1025 C. (say 900 C. to 950 0.).

At the termination of the final reduction,

ed to just above the critical range located ordinarily at 750 C.825 U.(for instance, 900 C.) and held for from 15 minutes to one hour, orlonger, at the maximum temperature thus selected according to the sizeand anal sis of the product, and then waterquenched or otherwise rapidlycooling.

In some instances, if desired, the prolonged heating within the range of200 (1., or thereabout, above the critical temperature located at about825 O.,continued until any carbids and the excess carbids of theeutectic have .been reabsorbed by the mix crystals,will be succeeded inthe same fun.

nace operation by the further heating to the higher temperatureshereinbefore referred to, without the intermediate light reductionspecified. In these instances, the ingot, when raised to thefinalequaliz'ed tem perature,) and suitably regrained, may be either sujected to reduction and then out up into billets or slabs, or, if theductility is suflicient for the particular final forming intended, itmay be rolled to final shape.

Having thus described my invention, what I claim is:

1. The method of producing a wrought shape of manganese steel from acast ingot wherein, during coolin there has been a separation ofeutectic w thin the mass of the metal, comprising heating the steel to atemperature within the ran e of 200 0., or thereabout, above thecritical tem erature located at about 825 (3., for a su ciently longperiod of time to permit the reabsor tion by the mix crystals of themetal of t e greater part of the excess carbidsof the eutectic, and anycar-bids which may have separated, ultimately heating the metal to atemperature suitable for the ductility required, andthen subjecting themetal to reuctlon. r 2. The method of producing a. wrought shape ofmanganese steel from a cast ingot wherein, during cool there has been a.separation of eutectic within the mass of the metal, comprising heatingthe steel to a temperature within the range of 200 0., or thereabout,above the critical tem erature cientiy long period of time to permit thereabsorption by the mix or greater part of t e excess carbide 0f theeutectic, and any carbids which may have stals of the metal of theseparated, ultimately heating the metal to and regraining it at atemperature suitable for the ductility ret uired, and then subject. ingthe metal to re uction.

3. The method of producing a wrought shape of manganese steel from acast ingot wherein, during cooling, there has been a separation ofeutectic within the mass of the metal, comprising heating the steel at atemperature within the range of 200 (3., or thereabout, above thecritical temperature located at about 825 (1., for a sufliciently longperiod of time to permit the reabsorption by the mix crystals of themetal of the greater part of the excess carbids of the eutectic and anycarbids which may have separated, then subjecting the-metal to aninitial reduction, re ieating it until it is regrained and has attaineda ductility appropriate to further reduction, and then subjecting it tosuch further reduction.

4. The method of producing a wrought shape of manganese steel from acast ingot wherein, during cooling, there has been a separation ofeutectic within the mass of the metal, comprising heating the steel to atem perature within the range of 200 C., or thereabout, above thecritical tempierature located at about 825 C., for a su ciently longperiod of time to permit the reabsorption by the mix or stals of themetal of the greater part oft \e excess carbids of the eutectic and anycarbids which may have separated, subjecting the metal to an initialreduction, cutting it into preliminary lengths for subsequent reduction,reheating at a temperature suitable for the ductility required for the f1rther reduction, andithen subjecting the metal to such further reduc---tion.

5. The method of producing a wrought shape of manganese steel from acast ingot wherein, during cooling, there has been a separation ofeutectic within the mass ofthe metal, comprising heating the steel toatomperature within the ran e of 200 Ci, or thereabout, above thecritical tem era'iture located at about 825 O., for a su ciently longperiod of time to permit the reabso'rption by the mix or stals of themetal of the greater part of t e excess carbids of the eutectic, and anycarbids which may have separated, ultimately heating the metal to atemperature suitable for the ductility required, then subjecting themetal to reduction, reheating the product slowl through the criticalrange located ordinari y at 750 C. to 825 (1., and wateruenching.

6. The method of pro ucing a wrought shape of manganese steel from acast ingot wherein, during cooling, there has been a separation ofeutectic within the mass of the metal, comprising heating the steel to atemperature Within the ran e of 200 0., or thereabout, above thecritical temperature located at about 825 0., for a sufficiently longperiod of time to permit the reabsorption by the mix crystals of themetal of the greater part of the excess carbids of the eutectic, and anycarbids which may have separated, ultimately heating the metal to ateuilperature suitable for the ductility require then subjecting themetal to reduction, reheating the product to a temperature above thecritical range located ordinarily at about 750 C.-825 C.,. continuingthe heating at the selected maximum temperature until the carbids of thesteel are taken into solution, and water-quenching.

In testimony whereof I afiix my signature, in presence oftwo witnesses.

WINFIELD s. POTTER.

Witnesses:

M. A. BI L, LEON W. ROSENTHAL,

Correctionin Letters Patent; No. 1,278,207.

It is braby certified that in Letters Patent No. 1,278,207,grmtodSoptamber-IO, ,1918, upon the application of winfiold S. P otterof Pittsburgh Pennsylvania, for

appcars tho printed specification con-action cs foilpwl; Pa-ga 1, line22, for the word above mod obouu'and Exit the said Lotion Paton? shouldroad with this correction therein that the comp may conform to thorecord of the cm in the Potent Ofiico.

{ Signed and healed this 29th day of October, A. 1m

V B. 1 wm mm,

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